1. Field of the Invention
The present invention relates to drug delivery devices, and, in particular, to drug delivery devices that utilize an aerosol generator to nebulize a drug solution.
2. Description of the Related Art
Nebulizers are well known in the art and may comprise a number of modules that can be selectively coupled to each other. For example, an electronics module can be provided for containing device electronics, including an aerosol generator, while an intermediate module may be provided for containing a pool of drug solution. In such systems, activation of the electronics module when the modules are not securely coupled may damage device electronics or lead to nebulization of drug solution into the atmosphere, or cause other problems, thus wasting the valuable medication.
Some nebulizing devices employ aerosol generators that nebulize a drug solution by transmitting acoustic waves from an acoustic wave generator to the drug solution via a fluid. In these known nebulizing devices, the fluid may damage other components within a nebulizing device due to thermal expansion. For example, the fluid may expand due to being exposed to low temperatures that bring the fluid to, or close to, a freezing point. The fluid will also expand when heated by ultrasonic energy associated with the acoustic waves passing therethrough. These expansions may damage nebulizing device components adjacent to the fluid, or may even crack the surrounding housing portions